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Finding the Fourth Proportional to 1,390.16, 1,918.74 and 918.15

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Solution

The fourth proportional to 1,390.16, 1,918.74 and 918.15 is: 1,267.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.16 : 1,918.74 = 918.15 : x
  2. Step 2: Convert to fraction form
    1,390.16/1,918.74 = 918.15/x
  3. Step 3: Cross multiply
    1,390.16x = 1,918.74 × 918.15
  4. Step 4: Simplify right side
    1,390.16x = 1,761,676.95
  5. Step 5: Solve for x
    x = 1,761,676.95/1,390.16
  6. Step 6: Final answer
    x = 1,267.25

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.